ANS and ENS Flashcards
Autonomic System
- The “self regulating” part of the nervous system controlling viscera, vasculature, glands
- Regulates homeostasis and reproduction
ANS can be largely influences by the CNS but also chemoreceptors, baroreceptors, mechanoreceptros to run automatically
Autonomic Afferent Systems Receptors
Mechanoreceptors
Chemoreceptors
Nociceptors
Thermoreceptors
Mechanoreceptors - ANS
Pressure
Baroreceptors in arteries (e.g. carotid sinus), lungs
Stretch
Veins, bladder, intestines
Chemoreceptors
- Carotid and aortic bodies (oxygen)
- Medulla (H, CO2)
- Hypothalamus (blood glucose, other electrolytes)
- Stomach/tongue/olfactory bulbs (various chemicals
Nociceptors
- Viscera and arterial walls
– Sensitive to stretch, ischemia, various irritating chemicals (e.g. inflammation)
Danger signs can be interpreted as pain
Thermoreceptors
Hypothalamus
* Blood temp
Cutaneous
* External temp
Information enters the CNS via:
- Spinal nerves through dorsal root to spinal cord
These then synapse with:
– Visceral efferents heading back out to organs (autonomic reflexes) Ex: Vomiting due to bad food
– Neurons ascending to brainstem, hypothalamus, thalamus
Visceral nociceptors also connect with:
– Somatosensory nociceptive afferents, contributing to referred pain
– Somatic efferents to skeletal muscle (muscle guarding); Goes back out to muscle tissue
— Ex: When sick you have tight muscles.
- Facial (VII), Glossopharyngeal (IX), Vagus (X)
– Info converges to solitary nucleus (in Medulla), the main visceral sensory nucleus
– From there, connections to:
— Pons and Medulla
— Hypothalamus, Thalamus, Limbic System
What does the Pons and Medulla do?
provide descending control to regulate HR, respiration, blood pressure, vasoconstriction/dilation
What does the hypothalamus, thalamus and limbic system do on the CNS?
Indirectly controls the Pons and Medulla
Visceral pain and referred pain
Visceral nociceptors may share the same dermatome or same transmitting neurons in the cord as somatosensory neurons
Constipation and Low Back Pain
- The two are often linked, confused, as constipation can cause muscle guarding
- Many pain medications make constipation worse – more muscle guarding – more back pain
- This can perpetuate a vicious cycle
How does the limbic system effect (psychological) effect the (physical) domain?
- Provides direct links between thoughts/beliefs, emotions, moods, and the overall state of the organism
- Part of the explanation for why stress kills people
- Or why how one feels about their job/spouse/life influences their pain experience
A ____ axon exits the central nervous system and synpases within a motor ganglion.
Basis of both sympathetic and parasympathetic nervous system pathways
myelinated
A ____ axon then exits this ganglion and travels to the target
Basis of both sympathetic and parasympathetic nervous system pathways
non-myelinated
Sympathetic Pathway: Origin and Pathway
- Originates: Hypothalamus
- Then goes through complicated multineuron pathway down to the intermediate column of the spinal cord between T1 and L2 Spinal Levels.
- Peripheral nerve exits the column through mixed spinal nerve to ventral ramus
- From ventral ramus enters the sympathetic trunk via white communicates
- Then travels up, down or out according to destination.
What is another name for intermediate column?
Lateral horn
Parasympathetic: Origin and Pathway
- Originates: Hypothalamus
- Long preganglionic/Short postganglionic
- Most parasympathetic innervation form 4 cranial nerves (Only pelvic parasympathetics arise from spinal cord)
4 Sympathetic Destinations
- Nearest Ganglion (via Gray Rami Communicates)
- Higher Ganglion (Cervical)
- Lower Ganglion (Abdominopelvic and Lower Extremities)
- Exit Ganglion -> Splanchnic N. (Abdomen/Abdominal Arteries and ENS)
5 Parasympathetic Pathways
- Oculomotor Pathway (constriction of the eye and shape)
- Facial Pathway (salivary glands)
- Glossopharyngeal Pathway (parotid gland)
- Vagal Pathway (between head and end of transverse colon
- Pelvic/Sacral Pathway (S2-S4; beginning of descending colon and out)
Peripheral Nerve Lesion - What happens to body functions?
- Lose motor, sensory and some sympathetics
- Examples:
– Loss of vascular control (constriction/dilation)
– Loss of temperature regulation – cold intolerance
– Loss of sweating in supplied skin
– Can lead to trophic skin changes (degeneration)
— Changes in color, texture, hair growth, nail beds
— Slower healing
— Dry, shiny, waxy appearance
SCI - Sexual Function
- Female: may eliminate sexual response BUT not ability to have sexual intercourse or ability to bear children
- Male: may lose ability for intercourse and conception
– Erection: Parasympathetic (Sacral/Reflex caused)
– Ejaculation: Sympathetic (Thoracic)
SCI levels and Male Erection and Ejaculation
Erection: REFLEX; Higher injury level = higher likeliness of function
Ejaculation: NOT REFLEX; May lose ability to conceive
Urination Control
3 Levels of Control: Cortical, Pons and Parasympathetics
* Higher level injury (Damage to Cortical and Pons) = Spastic bladder (REFLEX = Automatic void)
- CAUTION: Autonomic dysreflexia
- Lower level injury (Damage to Parasymp; S2-S4) = Flaccid Bladder (No contraction; Requires catheter)
Autonomic Dysreflexia
- Sympathetic response due to full bladder
- Leads to vasoconstriction = Increase in BP
- Baroreceptors sense increase in BP, sends signal to Medulla
- Medulla should send signal to parasympathetics and sympathetics; Parasympathetic via Vagus = decrease in HR; Sympathetic via thoracolumbar column should decrease BP but is damaged so BP continues to rise
- High BP and Low HR = DANGER
What autonomic NTs and Receptors are utilized for pharmacuticals?
- NTs: ACH, Norepinephrine (and epinephrine from the adrenal gland)
- Receptors for ACH: Nicotinic, Muscarinic
- Receptors for Norepinephrine:
– Alpha-1
– Alpha-2
– Beta-1
– Beta-2
What does the enteric nervous system do?
- Helps with motility in digestive tract (Myenteric Plexus)
- Monitors environment, regulates blood flow and epithelial function. (Submucous Plexus)
How does the ENS relate to PT practice?
- Dietary recommendations (Constipation/LBP)
- Pelvic health
- Visceral mobilization
Pupillary Consensual Response vs Direct Pupillary Response
Direct Pupillary Response: A bright light shown into one eye will stimulate the parasympathetic response of pupillary constriction
Consensual Pupillary Reponse: Other eye constricts
This is due to the information coming back to the optic chiasm and splitting both ways. Signal goes to parasympathetic oculomotor nucleus on each side. Sends signal out to both eyes to constrict.
